The rulebook that decides which running shoes are legal sets one ceiling of 40 millimetres for road races and another of 20 millimetres for the track. The table that did that also removed a number from the sport: 25 millimetres, which used to govern four separate event groups, no longer appears in it at all.
The current limits sit in Appendix 3 of the World Athletics Athletic Shoe Regulations, in a table titled “New Sole Thickness Table, in force from 1 November 2024”. It is one page long, it has five rows, and between those five rows it decides whether a shoe an athlete already owns can be worn in a permitted competition. Regulation 5.3 is blunt about that last part: from that date, an existing shoe with a sole thicker than the table allows is no longer approved.
Most of the coverage at the time reported the change as a single new figure, 20 millimetres for the track. The table itself is more interesting than that, for two reasons. The road figure did not move. And for three specific event groups, the change was a reduction, not an allowance.
What the sole thickness table actually says
These are the five rows of the table currently in force, with the conditions the regulation attaches to them.
| Event group | Maximum sole thickness | Condition stated in the regulation |
|---|---|---|
| Track events, including hurdles and steeplechase | 20 mm, spiked or non-spiked | In relays the limit follows the distance of the leg each athlete runs. Track race walking follows the road figure instead. |
| Field events | 20 mm, spiked or non-spiked | In jumping events, the sole at the centre of the forefoot must not sit higher than the sole at the centre of the heel. |
| Road events, running and race walking | 40 mm | No further condition. |
| Cross country | 20 mm with spikes, 40 mm without | Athletes may wear either. The applicable ceiling depends on which shoe they choose. |
| Mountain and trail races | Any thickness | No limit set. |
Two things fall out of that arrangement immediately. The road ceiling is exactly twice the track ceiling, a ratio of two to one. And cross country is the only discipline where both numbers are live in the same race, applied not by event but by what is on the athlete’s feet at the start.
The 25 millimetre limit that left the rulebook
The table that ran until 31 October 2024 is printed on the page before the current one, which makes the comparison easy to do and, as far as we can tell, one nobody published. Here it is, row by row, with the difference calculated by Raw POV.
| Event or shoe type | Until 31 Oct 2024 | From 1 Nov 2024 | Change |
|---|---|---|---|
| Track, under 800m, including hurdles | 20 mm | 20 mm | None |
| Track, 800m and above, including steeplechase | 25 mm | 20 mm | 5 mm lower |
| Field events except triple jump | 20 mm | 20 mm | None |
| Triple jump | 25 mm | 20 mm | 5 mm lower |
| Cross country, spiked shoe | 25 mm | 20 mm | 5 mm lower |
| Cross country, non-spiked shoe | 40 mm | 40 mm | None |
| Road running and race walking | 40 mm | 40 mm | None |
| Mountain and trail | Any | Any | None |
Three of the eight combinations tightened. Five did not move. Nothing loosened. Each of the three reductions is 5 millimetres, which is a fifth of the ceiling those events used to have. And the number 25 disappears completely: the sport went from three numeric ceilings, 20, 25 and 40, down to two.
Worth noting what that does to a wardrobe. A distance runner whose track shoe measured between 20 and 25 millimetres was inside the rules until 31 October 2024 and outside them the next morning, with no change to the shoe. The same shoe is still legal on the road, where the ceiling is 40. That is the practical shape of this rule: the shoe is not approved or unapproved in the abstract, it is approved for a surface.
Where the 40 millimetres are measured, and where they are not
The regulation does not measure the thickest part of the sole. It measures two specific points, and Regulation 10.4 defines them as percentages of the shoe’s internal length: the centre of the forefoot at 75 per cent, and the centre of the heel at 12 per cent. For a standard unisex size 42 sample, the document gives those as approximately 203 millimetres and approximately 32 millimetres from the inside back of the shoe. Then it says plainly that the thickness of the sole outside those two points is not relevant to compliance.
Run the two anchors backwards and they imply an internal length of roughly 271 millimetres from the forefoot figure and roughly 267 millimetres from the heel figure, a spread of about 4 millimetres. The regulation uses the word “approximately” for both, and Regulation 10.5 adds that a marginally thicker sole attributable only to a larger shoe size will be disregarded. So the sample size is a reference point, not a caliper reading.
Three more things sit outside the ceiling by design. A removable orthotic, a heel raise or heel cap, and a brace or strap are all treated under Regulation 7 as insertions and additions, and Regulation 7.2.5 states for the avoidance of doubt that they do not fall within the maximum thickness. Permanently fixing an extra inner sole inside the shoe is not allowed. The distinction the rule draws is between something you can take out and something built in.
One plate, eleven spikes, and a four millimetre gauge
Thickness is the headline number, but it is not the only one. Regulation 10.6 allows a shoe to contain no more than one rigid structure, a plate or a blade, whether it runs the full length of the shoe or part of it. That structure may come in more than one part, but the parts must sit in a single plane: no stacking, no overlap. A second rigid structure is permitted in exactly one situation, to attach spikes to the outer underside, and the regulation specifies it cannot be a continuation of the first. Embedded sensing or intelligent technology is not permitted at all, though a heart rate or speed monitor the athlete carries or wears is a separate matter.
The spike numbers are equally exact. Up to 11 spikes, and no more than 11 spike positions, which means a shoe cannot be built with 14 sockets and 11 spikes screwed into them. Projection from the sole or heel is capped at 9 millimetres outdoors and 6 millimetres indoors, rising to 12 millimetres for the high jump and the javelin throw. At least the half of the spike closest to the tip has to fit through a square sided 4 millimetre gauge. Two escape hatches follow: a track manufacturer or stadium operator can impose a stricter maximum or ban certain spike shapes, and in cross country the technical delegates can permit longer spikes depending on the surface of the course.
This is the third time we have gone through a governing body’s rulebook looking for the number rather than the announcement. The FIFA quality programme turned out to define a match ball by its permitted tolerances rather than its brand, and Canada’s athlete funding turned out to run on a monthly carding rate that is public and rarely quoted. Equipment definitions are where a lot of sports quietly decide what the sport is. Futsal is a whole discipline built around a ball that is deliberately made to bounce less.
The shoe also has to be something anyone can buy
The part of the regulation with the least attention on it may be Appendix 4. Existing and new shoes have to be available for purchase by any athlete competing in permitted competitions. For a new shoe, availability has to start no later than one month before the first competition at which the athlete plans to wear it, and a pre-order period counts as long as it lasts at least a month. Retail, brand websites, apps and e-commerce all qualify as sales channels.
There is no obligation to restock. If a shoe sells out, or the line ends, the regulation’s answer is that the athlete may wait or buy an alternative. But if a manufacturer cannot show evidence that the shoe was available, the shoe comes off the approved list, member federations are notified, and results achieved in it are marked “UNC TR5.2”, the code for uncertified.
Two categories sit at the edges of that scheme. A bespoke shoe, defined as a one-off made to order for a single athlete and never available for purchase, is not permitted in any applicable competition. A development shoe, one a manufacturer is still testing before it reaches the market, can be approved for a maximum of 12 months from the date the athlete first proposes to wear it, and is barred from World Athletics Series events and the Olympic Games.
What the table does not settle
It is worth being precise about the limits of this document. The regulation states ceilings and procedures. It does not publish a rationale for choosing 20 or 40, it does not rank materials, and it contains no claim about what any thickness of foam returns to a runner. Anyone reading the table for a verdict on whether thick soles work is reading the wrong document.
The regulation also has a discretion clause running through it. Regulation 10.1 opens with the words “unless specifically agreed by the Chief Executive Officer (or their nominee) in writing”, and Regulation 10.6 carries a similar carve-out for exceptional circumstances agreed by the Competition Commission. How often that discretion is used is not in the document, and we did not find a published record of it.
What the table does give a runner is a straight answer to a narrow question. Measure the sole at the centre of the forefoot and the centre of the heel. If the answer is over 20 millimetres, the shoe is a road shoe, a cross country shoe without spikes, or a trail shoe. If it is 20 or under, it can also go on the track.
Frequently asked questions
What is the maximum sole thickness allowed in road races?
40 millimetres, for both road running and road race walking. That figure did not change on 1 November 2024, and track race walking follows the road figure rather than the track one.
Where on the shoe is the sole thickness measured?
At two points only: the centre of the forefoot, at 75 per cent of the shoe’s internal length, and the centre of the heel, at 12 per cent. For a standard unisex size 42 sample the regulation gives those as approximately 203 millimetres and 32 millimetres from the inside back of the shoe. Thickness outside those two points does not count towards compliance.
How long can a spike be?
Projection from the sole or heel is limited to 9 millimetres outdoors and 6 millimetres indoors, except in the high jump and javelin throw, where it is 12 millimetres. A shoe may use up to 11 spikes and must not have more than 11 spike positions. Track operators can set a stricter limit, and cross country delegates can allow longer spikes depending on the course.
Sources and method
From the source. Every figure above comes from the World Athletics Athletic Shoe Regulations, Book C, C2.1A, approved by Council on 22 December 2021 and effective from 1 January 2022, in the version published by the federation as a PDF. The two sole thickness tables are Appendix 3. The measurement points are Regulations 10.3 and 10.4, insertions and additions are Regulation 7, plates and embedded technology are Regulation 10.6, spikes are Regulation 11, and the availability scheme is Regulation 13 with Appendix 4. The move to a unified 20 millimetre figure for track events from 1 November 2024 is also stated in the federation’s own press release. Regulation and press release: the shoe regulations PDF and the announcement of the new regulations.
Raw POV analysis. The row by row comparison of the two tables, the count of three tightened combinations out of eight, the calculation that each reduction is 5 millimetres or a fifth of the previous ceiling, the observation that the number 25 no longer appears, the two to one road to track ratio, and the internal length of roughly 267 to 271 millimetres implied by the two measurement anchors are all ours. The federation publishes both tables but does not publish the comparison.
What we could not establish. The regulation gives no stated rationale for the specific figures, and we found no published record of how often the written discretion in Regulations 10.1 and 10.6 has been exercised. We have not attributed a motive to any decision, and nothing here is a claim about how any shoe performs. Contact: hello@inkadigitalworks.com.
